Linear movement rudder pedal and linkage



1 9 E. c. WELLS 2,478,882

LINEAR MOVEMENT RUDDER PEDAL AND LINKAGE 4 Filed Dec. 15, 1944 2 Sheefs-Sheet 1 FIG.

INVENTOR. EDWARD C. WELLS ATTORNE Y6 Aug. 9, 1949. E. c. WELLS 2,478,882

' LINEAR MOVEMENT RUDDER PEDAL AND LINKAGE Filed Dec. 15, 1944 2 Shets-Sheet 2 INVENTOR. EDWARD C. WELLS i AT'roRArEm 32 I FIG. 2

Patented Aug. 9, 1949 UNITED STAT arrests LINEAR MOVEMENT RUBBER ANB LINK-AGE Edward Gr Wells Seattle, Wash, assignor to Boeing Airplane Company, a corporation of Delaware a a plication December 13, 1944, Serial No. 568,031

6 Claims. (Cl. 244-86) My invention pertains to an element movable lineslly, and more particularly to airplane rudderpeciai mechanism.

The direction of flight of an airplane is customanly controlled by a rudder whichis swung by application of force to apair of rudder pedals on which the pilot's: feet rest. These pedals are interconnected so that when one of them is pushed away from; the pilot the other moves tcrmdhlmc i A conventional rudder bar pivoted at the center is disposed exactly athwartships when the rudder is in neutrali As; such rudder bar is swung in either direction toswing the rudder correspondingly away from neutral position the pilots feet move somewhat: sidewise toward. a fore and aft-line'- through the rudder bar pivot beof the arc along which the rudder pedals fixed totherudtler bar move, althoug ii they travel principali y fore and aft.- Su'ch sidewise. movement decreases the leverage available. The fartrier the rudder is swung from: neutral position, however, the greater are the aerodynamic forces acting upon which tend to return it to neutral By the use of my arrangement a conventional rudder barpivoted at its center may be employed, but therudder pedals, instead of being mounted directly upon this pivoted bar, are connectedto it through linkage, and are guided by additional H'nkage-so-that in all swung positions of the: rudderbar therudder pedals travel directly fore and art and the leverage on the rudder bar is-thereforeconsta-nt.

It is a principal object of my invention taproride supporting and guiding mechanism for airplane rudder pedals, or other elements, which wiil constrain movement of such pedals or elements to a predete'nnined linear path.

A further object-is to control such movement of an element-bythe useoi pivoted linkagarather than by slideand guide mechanism or other types of structure employed heretofore to efiect suclrmotibna 1% further advantage or my mechanism is that it can be applied to a conventional type of cent'rally pivoted rudder bar without requiring: the liar mounting structure to be altered appreciably.

Characteristics of my li'nliag'e' for effecting linear motion generally, and mor particularly when incorporated in a rudder pedal mount, will be pointed out hereafter inthe specific description of apreferred form of 'my'invention.

Pligure 1 a side elevational view of airplane ruddcrpedal mechanismincorporating myinvcntier- Figure 2 is aplan view of such mechanism with a, portion of it broken away.

Figure 3 isa cross-sectional view taken through a rudder pedal journal on line 3-3 of-Figu're 2'.

Figure 4 is a cross-sectional view through the central portion-of the rudder bar and. its mounting alonglined-4 of Figure 21 v V The principles involved in the mechanismfor supporting andguiding the rudder pd'al'stobe described hereafter may be incorporated in mechanism oi varioustypes, and may take a variety of iorms'i The generalconstruction and characteristics ofsuch mechanism will bediscussed in corin.ection. with the specific application to the airplane rudderpedal mounting. illustrated in the drawing; 7 v o l The upright tubular shaft I may be connected in-l conventionalfashion to the rudder so that rotationof. tube l about its axis willl swingi the zrudder correspondingly, Suitable mechanismenabling the rudder bar to be shifted for accommodatingivarious leg lengths should be provided, lEt may include a bracket ll,. secured. to the upper of tube Lhaying integral with it a guideplate H extendingiore and aft; A slide 2; generally of channel shape, is carried by guide plate: ll and the downwardly projecting flanges of the slide embrace opposite edges of such guide plate. I This slide integral with the tubular rudder bar- 20, iandis bracedwith respect tosuch rudder bar by gusset webs 2h. The rudder bar can be displaced bodily ina fore and aft; direotioniby movement of slide! along plate H toadjust the positions of -.therudder.pedals. Y

-The rudder-bar 20 may beheld inuthe desired position oil adjustment by a=.pin 22 seating inone lofi several hol'sl-Z located at spaced intervals'in .the upper surface of guideplate I I. Thehead 23 of pin-22 is engaged over alifter bar 2* havinga slot 25' extending lengthwise of it,'througl'r which :the pin ifl isinserted The forward endof bar is pivotedbya pin 26170 an upwardly proj ectinig lug [3 carried by the-forward end ofguide plate fit-' Theirearward. end of such bar is normally held clown-by a spring 21- to dispose the barparal- .lel to theguide plate. Lug 28- is secured to' the lifter: bar near its: rearward end, to which maybe attached a suitable tension element, such as light cable. I When? itis desired to shift the rudder bar" 20 forward or rearward: lug-2% is raised to swing li fterbar 21 upward about its? pivot pin 26-. Such movement raises pin 22' to withdraw it from: the liole: t2 in whichaitwas lodgeda: The slide 2- may now-be: sbiftedforwardor rearward approximately the desired amount, whereupon the upward pull on lug 23 is discontinued. Spring 21 will then draw bar 24 downward, so that by shifting slide 2 slightly in one direction or the other pin 22 may drop into a diiierent socket l2 to fix the relationship of the rudder bar 20 and bracket In in the newly adjusted position.

Such rudder bar position adjusting mechanism would create an additional complication if the pedals were mounted directly on the rudder ba but my rudder pedal guide mechanism is equally I effective where such an arrangement is used. Since the center of the rudder bar does not coincide with the axis of the upright shaft I, as the rudder bar is swung in a clockwise direction as viewed in plan in Figure 2 it will be displaced bodily lengthwise to the right to a greater degree than if the shaft axis intersected the bar center,

because of the orbital movement of the rudder in all swung positions of the rudder bar and in .all adjusted positions of slide 2.

Each rudder pedal 3 is supported and guided for precisely linear movement by at least two sets of linkage, the movable end of each set being restricted to move in only a single plane. The movable ends of the particular linkages shown in the drawings are constrainedto move only in vertical and in horizontal planes, respectively, The rudder bar 23, swinging about the vertical axis of tubular shaft I, itself constitutes part of'the linkage system the end of which is movable only in a horizontal plane. A link 30 has one end pivoted by a vertical joint or journal 3| to one end of rudder bar 20, and its other end pivoted bya vertical journal 32 to one end of rudder pedal spindle 36. If no other restraint were placed upon the rudder pedal than that imposed by link 30 and rudder bar its spindle could assume any angular position in a single horizontal plane, and pressure on it in such plane would swing the rudder pedal about pivot 3| or 32 instead of swinging the rudder bar.

To the end of rubber pedal spindle 36 remote from pivot 32 linkage including links- 33 and 34 is connected. These links are joined by a horizontal pivot 35 and the end of link 33 remote from link 34 is pivotally connected to rudder pedal spindle 36. The end of link 34 remote from link 33 is pivoted by a horizontal bolt to the standard I 4 mounted rigidly upon floor l5 of the pilot's cockpit, or to an equivalent stationary support. Because the pivots 35 and 31 are horizontal, the end of link 33 remotefrom link 34 can move only in a vertical plane.

Since linkage 20, 30, 36, having vertical pivots, restrains movement of the joint between rudder pedal spindle 36 and link 33 to a horizontal plane, and since linkage 33, 34, having horizontal pivots, restrains movement of this joint to a vertical plane, such joint can traverse only a straight horizontal line defining the intersection of such vertical and horizontal planes.

It is further desired that spindle 36 should not swing in its horizontal plane, but always re main in an attitude perpendicular to its direction of movement insuch horizontal plane thus establinkages move are parallel.

lished by the vertical plane of linkage 33, 34. Con sequently it is necessary that a journal parallel to pivots and 37 of such linkage constitute this joint, instead of its being movable universally. Such journal insures that the spindle will remain perpendicular to its horizontal path of travel. 7

Two sets of linkages the movable ends of which move in intersecting planes will maintain linear movement of a rudder pedal or other element along the intersection line of the respective planes whether or not such planes are perpendicular. The more nearly such linkage planes approach mutual perpendicularity, however, the more effective and efiicient will be the control of the movable elements if only two linkage systems are employed. While two linkages are suiiicient for this purpose any number may be employed as long as all the lines of intersection of the respective planes in which the movable ends of such Thus all such linkage movement planes may intersect in a single line, or two such planes in parallel relationship may intersect a third linkage plane in parallel lines, or two linkage planesinclined relative to each other may intersect a third such plane in parallel lines. Also it is immaterial how many links are employed in each linkage as long as they permit linear movement of the movable linkage end in its plane throughout the desired range of movement.

Consideration of the load distribution between the linkages of such a system is of importance. Particularly is this true where'force applied to theguided element is to be transmittedto an anchor pivot of at least one of such linkages and converted into a torque acting on such pivot. In the instant case forward pressure on a rudder pedal produces a torque in shaft I. In addition forces acting transversely of the direction of rudder pedal movement must be. transmitted through the linkage system to the supporting structure. Thus the weight of the pedal, linkages, and the downward component of the .pressure exerted by the pilots foot is carried by the system. I V w When linkage such as 20, 30, 3B, requiring that rudder pedal 3 move in a horizontal plane, is employed in conjunction with linkage such as 33, 34, movable in a vertical plane, allthe vertical loads are carried by the former linkage. Instead of utilizing linkage movable in preciselya vertical plane to establish the direction of the horizontal line along which the rudder pedal must move, the plane of movement of linkage 33, 34 might be inclined although generally upright, as long as the direction of its line of inter section with thehorizontal linkage plane is not horizontal movement, although such an arrangement is most convenient for airplane rudder operating mechanism of the general type illustrated. For other applications, if the movable end of one linkage moves in a plane which is not precisely vertical the most accurate control can be obtained by combining with such linkage another linkage which moves in a plane substantially perpendicular to the first. If such linkages are each disposed at an angle of degrees to "vertical tha'grayity and other vertical: loans-will be shared: equally: by them. load relation;- ship be preserved; even; though such: inclined planes be.- disposed in intersect: along a slo ing ment to move in a straight line and of carrying V loads imposed. on such guided elementin directions transversely of its path of movement, as

discussed above. p y

In Figure 3 the bearings by which pedal 3 is journalled on it axle 36 are conventional. Preferably journal 32 also includes antifrictiou heat ings Spaced at each side otthc end of link 3.9 to prevent angular deflection of and rudder pedal spindle 36, and a' similar construction The pivot of link is incorporatedin pivot 3t. 33 onv rudder pedal spindle '36 is shown to inelude antifriction bearings, and the same construction. may be used for. pivots and, 31.

While the bearing structure illustrated is very efiective for preserving fidelity of movement when the guided element is subjected to heavy loads, it will be understood that the particular structure of such journals may be changed considerably, depending upon the requirements for each installation.

The mechanism described is all that is necessary to effect rotation of shaft l and consequent swinging of the rudder. Modern airplanes, however, are provided with wheel brakes which conventionally are operated by tilting the rudder pedal about a horizontal axis without swinging the rudder bar. Both the weight and forces for actuating such brake operating mechanism impose additional loads on the guided element. The brake operating mechanism may be of the hydraulic type, including a control valve 4 incorporated in the hydraulic brake system by conduits connected to openings in bosses 40 in customary fashion. One end of this valve is pivoted to a bracket 4|, secured to the rudder pedal spindle 36 so that it cannot move angularly about the spindles axis. The plunger 42 of valve l is pivoted to a lug 43 secured to the back of the treadle portion of the rudder pedal. As such treadle is tilted forward, therefore, plunger 42 will be shifted into the valve body to actuate the valve for applying the brakes. V

I claim as my invention:

1. Airplane rudder pedal mechanism comprising a substantially horizontal rudder bar, pivot means supporting saidrudder bar for rotation about its center, rudder pedals disposed generally parallel to the ends of said rudder bar at opposite sides of said pivot means, two horizontal links, each extending substantially perpendicular to said rudder bar and to said rudder pedals, and pivotally connected to one of said rudder pedals and to the corresponding end of said rudder bar to swing relative to both thereof about vertical axes, for restricting said rudder pedals to movement in a horizontal plane, two linkages, each supported by one end for movement confined to an upright plane generally perpendicular to said rudder bar, and pivot means connecting the unsupported ends of said linkages to said rudder pedals, respectively, to restrain movement of said rudder pedals transversely of said upright linkage planes and to guide them for movement, during swinging of the rudder bar, through positions r 6 alwaysporallel in the horizontal plane towhich movement of said rudder pedals is restricted by said horizontal links. and rudder bar,

2'. Airplane rudder pedal, mechanism. comprising: a substantially horizontal rudder bar. pivot means supporting said rudder bar ior rotation about centenrudder pedals; disposed generally 7 parallel to the ends, of said rudder bar atropposite sidesof said ptvot-meansttwohoriaontam links, each extendin substantiallupcrpendicular to said; ruddcrbar and to: saidrudder pedalsr. and

comectedto one of said. rudder pedals and to the. corresponding end of said rudder bar to swing relative to both, thereof about vertical axes, tor restricting said rudder.- pedals to move:- ment in a horizontal plane, two linkages, each supportedv by one. end for increment, confined to an upright plane genera-1m perpendioular'to said rudder bar, pivot means connecting the unmoaned ends or said linkages to said rudder pedals, respectivelmto restrain movement'v oi said 7 rudder pedals transversely o-isaid upright; lurkass Planes and to elude themrfor movement, durnmswins ng of; the rudder bar throush.nosi 1891 alw s parallel in. he horizontal plane-to which movement of said rudder pedals is restricted by said horizontal links and. said rudder bar, locking means normally operable to maintain said rudder bar pivot means stationary, and releasing means operable to release said locking means for bodily shifting of said rudder bar along a path perpendicular to said rudder pedals into a different adjusted position, and said holding mean being operable thereafter to maintain said rudder bar pivot means in such difierent adjusted position.

3. Airplane rudder pedal mechanism comprising a substantially horizontal rudder bar of considerable length, pivot means supporting said rudder bar for rotation about its center, rudder pedals disposed generally parallel to the ends of said rudder bar at opposite sides of said pivot means, each rudder pedal being located intermediate said pivot means and the adjacent end of said rudder bar, two horizontal links, each extending substantially perpendicular to said rudder bar and to said rudder pedal and pivotally connectedto one end of said rudder bar and to the adjacent end of the adjacent rudder pedal to swing relative to both thereof about vertical axes, for re- 7 stricting said rudder pedals to movement in a horizontal plane, two linkages, each supported by one end for movement confined to a'vertical plane generally perpendicular to said rudder bar, and disposed close to said rudder bar pivot means, and pivot means connecting the unsupported end of each of said linkages, respectively, to the end of the adjacent rudder pedal remote from the connection of such rudder pedal to it horizontal link, to restrain movement of said rudder pedals transversely of said vertical linkage planes and to guide them for movement, during swinging of the rudder bar, through positions always parallel in the horizontal plane to which movement of said rudder pedals i restricted by said horizontal links and said rudder bar.

4. Linear movement crank mechanism comprising a horizontally swingable crank, link means having an end movable in a substantially horizontal plane and its other end pivotally connected to the swinging end of said crank, further link means having an end movable only in a substantially vertical plane and having its other end anchored to rotate about a horizontal axis, and linearly movable operating means interconnecting the movableends of said two' link means.

5. Linear movement crank mechanism com-'- prising a horizontally swingable crank, further link means having an end movable in asubstantially horizontal plane and its other end pivotally connected to the swinging end of said crank, and the other linkage-having an end movable only in a substantially vertical plane and having its other end anchored to rotate about a horizontal axis, and linearly movable operating means such as a pedal rod interconnecting the movable ends of said two link means, the axis of swing of said crank being'ofiset appreciably from the above-said'vertical plane which is parallel 'to the line of said linear movement. F

6; Linear movement crank mechanism comprising a horizontally swingable crank, a link havingan end movable in asubstantially horizontal plane and its other end pivotally connected to the swinging end of said crank, the body of said link being disposed normally substantially at right angles to the cranks moment arm, link means having an end movable only in a substantial vertical plane and having its other end an- Tchored to "rotate about :a horizontal i axis; and pedal-rod means having pivotaljoint means at opposite endsthereof; securing said link to such movable end-of said link means, said pivotal joint means secured to said link means restraining movement of said pedal rod out of a position substantially perpendicular to the verticalplane or movement of such movable end of said'link means. 2 7

EDWARD C. WELLS. V I REFERENCES CITED The' following references are of record in the file of this patent: UNITED STATES PATENTS I Germany Nov; 30, 1938 Certificate of Correction Patent N 0. 2,47 8,882 "August 9, 1949 EDWARD O. WELLS It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 7, line 4, strike out the word further; line 8, for and the other linkage read further link means; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Ofiice.

I Signed and sealed this 27th day of December, A. D. 1949.

THOMAS F. MURPHY,

Assistant Uommz'au'oner of Patentl. 

